This invention relates to vacuum sizers for extruded plastic profiles, and more particularly the present invention relates to modular vacuum sizing devices which are such that differing vacuum sizer dies can be assembled and disassembled into a vacuum sizer box without the necessity to realign the dies.
The art of extruding complicated profiles and shapes of an extrudable thermoplastic material, for subsequent use in many different manners, is well known. For example, many different forms of extruded plastic are used as parts, body trim, and so on, on automobiles. Other extruded plastics materials are used for such purposes as picture framing and the like. Still other examples for the use of extruded plastic materials include trim around bathtubs, door openings, door edges of cabinet doors used in bathrooms and kitchens, and so on.
However, there are several fields in which highly complicated extruded plastics profiles are used, where the size or calibration of each profile is critical. One field, in particular, where such criteria exist is the field of windows and doors which are made for domestic, industrial, and commercial purposes, where the frame of the window or door into which window glass or a door panel is placed, or the outer frame which is placed in a suitable wall opening, are formed in extruded plastic. Because different profiles fit to one another, or must have specific dimensions so as to accommodate the placement of glass panels, for example, or may sometimes be formed as a co-extrusion of a hard plastics material with a soft plastics material which may be intended to be used as a sealer or gasket, the ability to produce the plastic extrusions with defined dimensions having very small tolerances, is critical.
Accordingly, a body of art has been developed in respect of vacuum sizing boxesxe2x80x94sometimes referred to as vacuum calibratorsxe2x80x94through which the extruded plastic profile is passed, and in which the size or dimensions of the extruded plastic profile are carefully controlled by the use of vacuum to pull the plastic material to the outer edges of a specifically shaped passageway as the extruded profile is passed therethrough. However, the construction of vacuum sizer boxes is very expensive. Each box requires a base plate, a top plate, and side plates, together with appropriate connections to cooling water and vacuum pumps so as to cool and size the extrusion as it passes through the vacuum sizer box. Heretofore, it has been necessary to build a different and complete vacuum sizer box for each different profile which is to be extruded. Changing vacuum sizer boxes to accommodate a different profile has required considerable down time of the extrusion line.
Still further, it sometimes happens that the extrusion line must be stopped for one reason or another and, if so, it may be necessary to disassemble the vacuum sizer box, take out the sizing dies and clean them, and then reassemble the vacuum sizer box. Heretofore, that has meant that the vacuum sizer dies in the vacuum sizer box must be realigned, which is a lengthy, time-consuming process, resulting in still further down time for the extrusion line.
As an example, every time an ordinary vacuum sizer box is required to be disassembled, vacuum lines and water hoses must be disconnected and, of course, the alignment of the passageways of individual dies which are bolted together inside the vacuum sizer block is lost. One approach that has been taken in the past to avoid the requirement for realignment has been to create sizing dies which have longer lengths. That, in turn, has significantly increased the cost of production of such dies.
On the other hand, the present invention significantly decreases the cost of production of vacuum sizing boxes, and it significantly decreases the down time of an extrusion line either for changing vacuum sizing boxes to accommodate a different profile, or to clean the dies. These advantages are achieved primarily by the provision of a pre-assembled base plate and side plate for a vacuum sizing box, which provide reference planes arranged perpendicularly one to the other. Then, a plurality of vacuum sizer die elements is provided, each of which is rectangular (or square) and each of which has two reference surfacesxe2x80x94one at the bottom and the other at one sidexe2x80x94which fit against the reference planes provided by the bottom plate and side plate. The vacuum sizing profile is carefully and precisely machined into each vacuum sizer die element, with particular emphasis on the placement of the profile with respect to the reference surfaces which have been machined on two sides of the die to fit against the reference planes. Thus, assembly or reassembly of the vacuum sizer box is easily accommodated without the necessity for realignment of the die elements.
Moreover, the present invention provides that the vacuum lines and water lines may be permanently connected to the vacuum sizer box, by connecting vacuum lines to the base plate and providing appropriate holes and slots in the base plate and one or more of the die elementsxe2x80x94as described hereafter.
Also, removable side plates can be fitted with water passageways, so there is no necessity for connecting, disconnecting, and/or reconnecting of water lines.
Thus, in keeping with the present invention, it is merely necessary to place a new group or groups of vacuum sizer die elements against the reference planes which are fitted permanently in place in the extrusion line, and then reassemble the other side plate or plates, and top plate of the vacuum sizer box, all of which can be done quite quickly and without the necessity to realign the die elements.
In the usual practice of the present invention, as discussed in greater detail hereafter, the individual vacuum sizer die elements are cut into two sections, an upper section and a lower section, which makes assembly and cleaning much easier and quicker. Moreover, testing and proving the vacuum sizer die elements may be made easier, especially if it may develop that there is a necessity to provide for an additional or further vacuum domain in any particular region of the profile. As will become evident hereafter, the placement and/or relocation of vacuum passages in vacuum sizer die elements in keeping with the present invention, is simplified over that which has gone before.
DeZEN Canadian Patent No. 1,154,218 teaches a vacuum sizing device which includes a plurality of pairs of upper and lower sizing elements that are clamped between upper and lower backing members. However, all of the lower elements are identical to one another, and all of the upper elements are identical to one another; and each of the upper and lower elements is such that it has uniform cross-sectional shape throughout its length. Each individual element is individually attached to both a source of vacuum and a source of cooling fluid, and contains a vacuum chamber and a cooling fluid chamber. Assembly and disassembly of the vacuum sizing device requires connection, disconnection, and/or re-connection, of a plurality of vacuum and cooling fluid conduits.
MELKONIAN U.S. Pat. No. 5,288,218 teaches an extrusion calibrating apparatus which is connectable to external sources of cooling and vacuums, and which is for use in the calibration of exterior profiles of hollow thermal plastic extrusions. The assembly of the extrusion calibrating apparatus includes upper and lower cover plates, each having a pair of vacuum manifolds, together with upper and lower vacuum plates each having vacuum slots and supply and return water channels, and a heat conducting calibrating insert which is removably positioned within an interior chamber between the vacuum plates. The removable heat conducting calibrating insert is designed to pass through an access opening formed when an upper cover plate and the upper vacuum plate are rotated into the open position. The insert has a forward face and rearward face, with the calibrating aperture corresponding to the exterior profile of the extrusion extending lengthwise through the insert between its forward and rearward faces. An xe2x80x9cOxe2x80x9d-ring seal is used to provide a seal between the front and rear cover plates and the insert forward and rearward faces, so as to prevent cooling water from passing therebetween and entering the calibrating aperture. The external water and vacuum sources are permanently connected to the calibrator box, while the calibrator insert may be removed. The lower cover plate remains fixedly attached to a stationary base or support, and thus the calibrator box remains aligned with the extrusion die. The only element which requires to be machined is the calibrating insert. However, it is but a single calibrating insert, requiring specific sealing in the box, and requiring vacuum manifolds, all of which increase the cost and may increase down time in the event of the necessity to clean the calibrator die.
A further United States patent to MELKONIAN et al., being U.S. Pat. No. 5,316,459, teaches a similar extrusion calibrating apparatus to that described above. The calibrating aperture has a forward opening in the forward face to allow the entry of the extrusion into the forward opening, and insert slots are positioned to intercept with the calibrating aperture so as to communicate a vacuum to the thin wall of the extrusion as it passes through the calibrating aperture.
Pxc3x9cRTSLINGER U.S. Pat. No. 5,514,325 teaches an apparatus and process for cooling and, if necessary, calibrating elongated continuously extruded objects made of plastic. The housing interior is divided by support diaphragms into a plurality of consecutive regions. The extrusion passes into the housing and through the consecutive support diaphragms, and the object is discharged at the outlet region. A cooling liquid is circulated throughout the consecutive regions, and a calibrating device may be used to guide and stabilize the cross-sectional shape of the objects passing through the housing.
CADWELL U.S. Pat. No. 5,607,638 teaches a vacuum sizing apparatus and method of cooling and sizing plastic extrusions. Extrudate from the extrusion die enters the vacuum sizing chamber through an entry sizing plate manifold. This maintains or imparts the size and shape of the extrudate as it enters the vacuum chamber. The entry sizing plate manifold may be of substantially reduced thickness relative to the initial sizing tool typically used in water or vacuum sizing tanks. The vacuum pressure applied to the entry and exit sizing plate manifolds acts as a seal to reduce water leakage from the vacuum chamber.
U.S. Pat. No. 5,780,071 to RACIOPPI et al. teaches a series of pre-aligned calibrators on a base, where the first section of calibrators is connected to the base and a second set of calibrators is connected to the table. This arrangement is so as to allow for thermal expansion of the base. A particular method for alignment of the calibrators is taught, but it is noted that the calibrators must be aligned. The calibrators themselves are provided with internal manifolds and vacuum ports, as well as an internal passage for a liquid coolant. The calibrators collectively define a linear extrusion pathway that limits damage to the surface finish, avoids internal strains, and otherwise is said to preclude unwanted results. The calibrators are mounted on a base so as to pre-align the extrudate pathway before the calibrators are installed on the extrusion line, and the emphasis of the patent is to the pre-alignment of the calibration devices on the base platform.
In accordance with one aspect of the present invention, there is provided an apparatus for cooling and sizing an extruded plastic profile as the extruded plastic profile is advanced forwardly in a longitudinal direction from an extrusion die. The apparatus of the present invention is modular in nature.
The apparatus of the present invention is connected to a source of cooling water, and includes at least one water passage through which cooling water or other cooling fluid will flow. The apparatus is connected to at least one vacuum pump, and includes vacuum passages and vacuum chambers within the apparatus, so that vacuum domains may be set up within the apparatus.
The apparatus comprises a base plate, a first side plate, at least one second side plate, a top plate, and a plurality of vacuum sizer die elements. Each of the plurality of vacuum sizer die elements has a passageway therethrough, which is in the shape of an extruded plastic profile to be cooled and sized by being advanced in a longitudinal direction through the apparatus. The plurality of vacuum sizer die elements are arranged sequentially in at least one group with the first die element in any group of die elements being that which is closest to the end of the apparatus which faces an extrusion die when the apparatus is in its operative position. The respective passageways of the contiguous die elements are aligned one with another.
At least one water passage is formed in at least one of the base plate, the first side plate, the at least one second side plate, and the top plate. Typically, as discussed hereafter, the at least one water passage is provided in the at least one second side plate, but it might also be provided in the top plate.
At least one vacuum chamber is formed in at least one face of at least vacuum sizer die element in the at least one group of die elements. That at least one face contacts another face of a contiguous vacuum sizer die element in the same group. There is at least one vacuum slot which extends from the at least one vacuum chamber to the outer periphery of the passageway, so as to provide vacuum communication from the passageway to the vacuum chamber.
The at least one vacuum chamber is in vacuum communication through a respective passage formed in the base plate, with the at least one vacuum pump.
The present invention provides that the base plate and the first side plate are permanently connected one to the other so as to provide a pair of reference planes defined thereby, the reference planes being perpendicular to each other. Each of the vacuum sizer die elements is formed with two faces which are perpendicular to the longitudinal direction, and each vacuum sizer die element has four sides forming a rectangular periphery. Two of the four sides of each of the vacuum sizer die elements, which two sides are perpendicular to each other, are precisely machined so as to be reference sides of each respective die element, and those reference sides of each of the plurality of the vacuum sizer die elements fits to the reference planes defined by the base plate and the first side plate. The passageway formed in each of the plurality of vacuum sizer die elements is placed with precise relationship to the respective reference sides of each respective vacuum sizer die element.
The outer dimensions of the respective passageways of the contiguous die elements may be reduced from the first die element in any group of die elements to the last die element in that group of die elements.
Moreover, the dimensions of the passageways of at least more than one of the plurality of vacuum sizer die elements in any group of die elements may be progressively diminished from one face to the other of each of the respective vacuum sizer die elements.
Typically, each of the plurality of vacuum sizer die elements is split into upper and lower sections. When the upper and lower sections of each of the plurality of vacuum sizer die elements are assembled together, they thereby define the passageway through which the extruded plastic profile will pass and be sized or calibrated.
A typical arrangement, in keeping with the present invention, provides for two groups of vacuum sizer die elements assembled in the apparatus. In such assembly, there are two second side plates, one for each of the two groups of vacuum sizer die elements.
Moreover, in an assembly such as that described immediately above, typically there is at least one water passage formed in each of the two second side plates.
The water passage which may be formed in each of the second side plates may be in the form of a groove which is cut into the outer surface of each of the second side plates, together with a cover plate which is placed against the respective outer surface of each of the second side plates, and connected thereto, so as to define the water passage in the groove and confined by the cover plate.
When there are two groups of vacuum sizer die elements assembled into the apparatus of the present invention, the first side plate may be provided having an opening formed therein, and the two groups of vacuum sizer die elements are placed in the apparatus so as to be positioned with one group on each side of the opening.
Each group of vacuum sizer die elements, when assembled, is clamped together. The vacuum sizer elements may be clamped together by a plurality of bolts passed through a plurality of respective bolt holes formed in each of the vacuum sizer die elements. They may also be clamped together by being placed between a pair of setting blocks which are secured to at least one of the base plate and the first side plate, where at least one set screw extends through one of the setting blocks so as to be advanced against the endmost vacuum sizer die element, and thus so as to urge the group of vacuum sizer die elements into a clamped together relationship.
There may be a plurality of vacuum pumps in vacuum communication with a plurality of vacuum chambers. Thus, the vacuum pressure existing in the respective vacuum domains throughout the apparatus, as defined by the respective vacuum chambers with which they are in vacuum communication, may be varied from one vacuum domain to another.
In a particular embodiment of the present invention, at least one vacuum chamber is formed in each respective vacuum sizer die element in each group. In another embodiment, vacuum domains of at least two vacuum sizer die elements are in vacuum communication with a single vacuum chamber.
When the apparatus of the present invention is assembled, typically there is a tongue and groove fitment between the baseplate and the at least one second side plate; and also between the top plate and each of the first side plate and the at least one second side plate.
In general, each of the base plate, first side plate, at least one second side plate, top plate, and the plurality of vacuum sizer die elements, is machined from aluminum.
Where there are two groups of vacuum sizer die elements arranged in the apparatus, especially in the circumstance where they are positioned at each side of the opening formed in the first side plate, a thermal break exists in the region of the opening in the first side plate.
A provision of the present invention is that differing groups of vacuum sizer die elements, having different passageways in the shape of different respective extruded plastic profiles, may be placed into the apparatus by fitment of the respective reference sides of each of the respective group of vacuum sizer die elements to the reference planes. Subsequently, the top plate and the at least one second side plate are assembled so as to place the apparatus of the present invention in operative condition.
In one embodiment of the present invention, a plurality of vacuum passages extend through each one of the vacuum sizer die elements, and at least on slit extends from each of the vacuum passages to the outer periphery of the passageway. This arrangement provides vacuum communication from the passageway to the plurality of vacuum passages.
In another embodiment of the present invention, there is a vacuum slot formed in at least one face of at least one vacuum sizer die element in the at least one group thereof; and this arrangement provides vacuum communication from the passageway to the at least one vacuum chamber formed in the at least one face.
Thus, an object of the present invention is to provide a modular apparatus comprising a plurality of vacuum sizer die elements, which may be changed with a minimum of effort and in a minimum amount of time.
Still further, the present invention provides for an apparatus for cooling and sizing an extruded plastic profile, where the cost of production of the apparatus may be reduced, resulting in savings of production costs for the extruded plastic profile as it is manufactured.
Yet another object of the present invention is to provide for a vacuum sizer box whose assembly and disassembly do not require connecting and disconnecting either vacuum or cooling water lines which are connected thereto.
These and other objects and features of the present invention are described in greater detail hereafter.